This data release consists of 1,984 line-kilometers of airborne electromagnetic (AEM), magnetic data and radiometric data collected from October to November 2017 in the upper East River and surrounding watersheds in central Colorado. The U.S. Geological Survey contracted Geotech Ltd. to acquire these data as part of regional investigations into the geologic structure and hydrologic framework of the area. The AEM data have been inverted to produce a series of regional cross-sections that constrain the electrical properties of the subsurface to a depth of ~500m. Data were acquired using the VTEM ET time-domain helicopter-borne electromagnetic system along flight lines that cross important geological structures over a 483 square kilometer area. In addition to magnetic and radiometric data, this data release includes minimally processed AEM data, processed AEM data used in the development of resistivity and induced polarization (IP) models, and laterally constrained inverse models for resistivity and IP parameters along all flight lines. Data that intersected cultural infrastructure have been removed from the processed AEM data prior to inversion.

This data release consists of 1,984 line-kilometers of airborne electromagnetic (AEM), magnetic data and radiometric data collected from October to November 2017 in the upper East River and surrounding watersheds in central Colorado. The U.S. Geological Survey contracted Geotech Ltd. to acquire these data as part of regional investigations into the geologic structure and hydrologic framework of the area. The AEM data have been inverted to produce a series of regional cross-sections that constrain the electrical properties of the subsurface to a depth of ~500m. Data were acquired using the VTEM ET time-domain helicopter-borne electromagnetic system along flight lines that cross important geological structures over a 483 square kilometer area. In addition to magnetic and radiometric data, this data release includes minimally processed AEM data, processed AEM data used in the development of resistivity and induced polarization (IP) models, and laterally constrained inverse models for resistivity and IP parameters along all flight lines. Data that intersected cultural infrastructure have been removed from the processed AEM data prior to inversion.

This data release consists of 1,984 line-kilometers of airborne electromagnetic (AEM), magnetic data and radiometric data collected from October to November 2017 in the upper East River and surrounding watersheds in central Colorado. The U.S. Geological Survey contracted Geotech Ltd. to acquire these data as part of regional investigations into the geologic structure and hydrologic framework of the area. The AEM data have been inverted to produce a series of regional cross-sections that constrain the electrical properties of the subsurface to a depth of ~500m. Data were acquired using the VTEM ET time-domain helicopter-borne electromagnetic system along flight lines that cross important geological structures over a 483 square kilometer area. In addition to magnetic and radiometric data, this data release includes minimally processed AEM data, processed AEM data used in the development of resistivity and induced polarization (IP) models, and laterally constrained inverse models for resistivity and IP parameters along all flight lines. Data that intersected cultural infrastructure have been removed from the processed AEM data prior to inversion. The data provided in this section include fully processed electromagnetic data produced from minimally-processed AEM data and used to develop inverted resistivity models. Digital data are described in the data dictionary and additional documentation is provided in the metadata.

This data release provides digital flight-line and gridded data for a high-resolution airborne magnetic and radiometric survey over the region surrounding the Wet Mountains of southern Colorado, including parts of Custer and Fremont Counties. Data for this survey were collected by Sander Geophysics Limited International (SGL) under contract with the USGS. The survey was flown in June and July of 2021 using a helicopter equipped with a magnetometer mounted in a stinger extending from the nose of the aircraft and a gamma-ray spectrometer stowed onboard. The helicopter pilots followed pre-planned flight paths in a grid-like pattern, with east-west lines spaced 150 meters apart and north-south lines spaced 1,000 meters apart. A terrain clearance of 80 meters above ground could be realized in areas of low relief to maximize detection of gamma-rays, but higher clearances, as much as 200-500 meters, were required over rugged terrain and populated areas for safety reasons. A total of 17,032 kilometers were flown along the lines, covering a 2,200 square-kilometer irregular area. SGL performed extensive data processing after completion of flying and delivered the final data and report in February 2022.

This data release provides digital flight-line and gridded data for a high-resolution airborne magnetic and radiometric survey over the southwestern portion of the Colorado Mineral Belt, southwestern Colorado. The Colorado Mineral Belt is a broad, northeast-southwest trending alignment of historic mining districts that have produced multiple types of commodities, including critical minerals that are vital to the Nation's security and economy. The survey was acquired as part of the UGSS Earth Mapping Resource Initiative (Earth MRI) to improve our understanding of the fundamental geologic framework underpinning the Colorado Mineral Belt. This release covers the southwestern portion of the belt (southwest block), which includes a wide swath from the Gunnison and San Juan mining districts on the northeast to the La Plata mining district on the southwest, including parts of Chaffee, Gunnison, Saguache, Hinsdale, Mineral, Ouray, San Miguel, San Juan, Dolores, Montezuma, and La Plata Counties. Previous reports have identified several critical minerals in this region, including aluminum, antimony, fluorspar, manganese, tungsten, vanadium, and zinc. Data for this survey were acquired by NV5 Geospatial, Inc. and is sub-contractors Precision GeoSurveys, Inc. and EDCON-PRJ, Inc under contract with the USGS. The survey was flown in September and October of 2023 using a helicopter equipped with a magnetometer mounted in a stinger extending from the nose of the aircraft and a gamma-ray spectrometer stowed onboard. The helicopter pilots followed pre-planned flight paths in a grid-like pattern, with north-south lines spaced 200 meters apart and east-west lines spaced 1,000 meters apart. Lines were flown 100 meters above ground as much as possible to maximize detection of gamma-rays and resolve details of the magnetic field. This clearance could be realized in areas of low relief but higher clearances, as much as 200-500 meters, were required over rugged terrain and populated areas for safety reasons. Areas with restricted airspace, such as Wilderness Areas, were avoided. A total of 28,472 linear kilometers of data were collected along the lines, covering a 4,719 square-kilometer irregular area. EDCON-PRJ performed extensive data processing after completion of flying and delivered the final data and report in April 2024.

Airborne electromagnetic (AEM) and magnetic survey data were collected during November and December 2016 along 4,212 line-kilometers over Yellowstone National Park, Wyoming. The survey was conducted as part of a study of the subsurface geologic structure and geothermal and groundwater resources of Yellowstone National Park. The survey was designed to image the subsurface plumbing of Yellowstone's myriad thermal features by constraining the geometry of the major hydrostratigraphic contacts and mapping regional-scale geologic structures. Data were acquired by SkyTEM ApS with the SkyTEM 312M time-domain helicopter-borne electromagnetic system together with a Geometrics G822A cesium vapor magnetometer. The survey was flown along six block-style line groups with a nominal line spacing of 450 meters (m), one block-style line group with a nominal line spacing of 250 m, two block-style line groups with a nominal line spacing of 150 m, and a series of regional reconnaissance lines with 5 km nominal line spacing. Due to terrain complexity, the mean flight height was about 48 m. The AEM depth of investigation varies considerably with subsurface resistivity, however the maximum depth of investigation is about 500 m. This data release includes minimally processed (raw) AEM and magnetic data as delivered by the contractor. A subsequent data release will include processed AEM data and inverted resistivity models used for USGS interpretation. Minimally processed digital data from production flights are provided and described in an accompanying data dictionary in open data format. The complete data package received from the contractor is included in a separate zip-file directory and described in the contractor's report (pdf file included with this data release).

Magnetic data collected as part of a high-resolution airborne magnetic and radiometric survey over the region surrounding the Wet Mountains of southern Colorado, including parts of Custer and Fremont Counties, are provided as digital flight-line and grid files. Magnetic surveys measure subtle variations in the Earth’s magnetic field and are sensitive to differences in the magnetic properties of rocks from ground level to many kilometers below. Data for this survey were collected by Sander Geophysics Limited International (SGL) under contract with the USGS. The survey was flown in June and July of 2021 using a helicopter equipped with a magnetometer mounted in a stinger extending from the nose of the aircraft. The helicopter pilots followed pre-planned flight paths in a grid-like pattern, with east-west lines spaced 150 meters apart and north-south lines spaced 1,000 meters apart. A terrain clearance of 80 meters above ground could be realized in areas of low relief, but higher clearances, as much as 200–500 meters, were required over rugged terrain and populated areas for safety reasons. A total of 17,032 kilometers were flown along the lines, covering a 2,200 square-kilometer irregular area. SGL performed extensive data processing after completion of flying and delivered the final data and report in February 2022.